In Sri Lanka, a state of emergency has been imposed following the assassination of Foreign Minister Lakshman Kadirgamar by unidentified gunmen. The military say the Tamil Tigers are the prime suspects in the fatal shooting but the rebels have denied any involvement.

Sri Lankan President Chandrika Kumaratunga appealed for calm and restraint after declaring a national emergency Saturday.

Police stepped up search operations, and soldiers set up roadblocks in Colombo, where Foreign Minister Lakshman Kadirgamar was shot in the garden of his heavily guarded home late Friday. Police believe two snipers carried out the attack.

President Kumaratunga says Mr. Kadirgamar was killed by "political foes." Mr. Kadirgamar was seen as a tough opponent of the Tamil Tiger rebels, and was considered a rebel assassination target.

Mr. Kadirgamar's killing comes at a critical time when a three-year cease-fire in the country is under increasing strain as the Tamil Tigers accuse the government of supporting a breakaway rebel faction.

Political commentators like Rohan Edresinghe at Colombo's Center for Policy Alternatives say it is no surprise the military is blaming the Tamil Tiger rebels for the shooting.

"There is widespread speculation it is the work of the Tamil Tigers because Mr. Kadirgamar was one of the most protected political leaders in Sri Lanka, and it is probably only an organization with the capacity of the Tamil Tigers could have carried out such an assassination," said Rohan Edresinghe.

The Tigers have been blamed for killing several high-ranking political leaders during the 20 years they waged a civil war for a separate Tamil homeland.

The violence ended after the 2002 cease-fire, but in recent months there has been a surge of attacks in the volatile eastern region, occasionally spilling into the capital, Colombo. Soldiers, rebels and civilians have been killed in these attacks.

The Norwegian team monitoring the Sri Lankan truce has called the foreign minister's killing a "serious blow" to the cease-fire.

The concern is echoed by political analysts like Mr. Edresinghe.

"There has been a lot of shock and a certain amount of fear that the ceasefire could now be really in jeopardy," he said. "Probably the Tamil Tigers were trying to remind the Sri Lankan government of their military strength and their military prowess."

The Tamil Tigers have criticized the imposition of the state of emergency, which allows the government to freely deploy troops. A military spokesman says helicopters are being used to monitor Tamil Tiger movement.

Several countries including the United States have strongly condemned Mr. Kadirgamar's killing.